Fix associative-commutative relations and the use of term walk groundedness

kanren/core.py

@@ -1,12 +1,13 @@
-from collections.abc import Generator, Sequence
+from collections.abc import Generator, Mapping, Sequence
 from functools import partial, reduce
 from itertools import tee
 from operator import length_hint
+from statistics import mean
 
-from cons.core import ConsPair
+from cons.core import ConsPair, car, cdr
+from multipledispatch import dispatch
 from toolz import interleave, take
 from unification import isvar, reify, unify
-from unification.core import isground
 
 
 def fail(s):
@@ -113,18 +114,25 @@ def conde(*goals):
 lany = ldisj
 
 
-def ground_order_key(S, x):
+@dispatch(Mapping, object)
+def shallow_ground_order_key(S, x):
     if isvar(x):
-        return 2
-    elif isground(x, S):
-        return -1
-    elif issubclass(type(x), ConsPair):
-        return 1
-    else:
-        return 0
-
-
-def ground_order(in_args, out_args):
+        return 10
+    elif isinstance(x, ConsPair):
+        val = 0
+        val += 1 if isvar(car(x)) else 0
+        cdr_x = cdr(x)
+        if issubclass(type(x), ConsPair):
+            val += 2 if isvar(cdr_x) else 0
+        elif len(cdr_x) == 1:
+            val += 1 if isvar(cdr_x[0]) else 0
+        elif len(cdr_x) > 1:
+            val += mean(1.0 if isvar(i) else 0.0 for i in cdr_x)
+        return val
+    return 0
+
+
+def ground_order(in_args, out_args, key_fn=shallow_ground_order_key):
     """Construct a non-relational goal that orders a list of terms based on groundedness (grounded precede ungrounded)."""  # noqa: E501
 
     def ground_order_goal(S):
@@ -134,7 +142,7 @@ def ground_order_goal(S):
 
         S_new = unify(
             list(out_args_rf) if isinstance(out_args_rf, Sequence) else out_args_rf,
-            sorted(in_args_rf, key=partial(ground_order_key, S)),
+            sorted(in_args_rf, key=partial(key_fn, S)),
             S,
         )
 
@@ -144,6 +152,48 @@ def ground_order_goal(S):
     return ground_order_goal
 
 
+def ground_order_seqs(in_seqs, out_seqs, key_fn=shallow_ground_order_key):
+    """Construct a non-relational goal that orders lists of sequences based on the groundedness of their corresponding terms.  # noqa: E501
+
+    >>> from unification import var
+    >>> x, y = var('x'), var('y')
+    >>> a, b = var('a'), var('b')
+    >>> run(0, (x, y), ground_order_seqs([(a, b), (b, 2)], [x, y]))
+    (((~b, ~a), (2, ~b)),)
+    """
+
+    def ground_order_seqs_goal(S):
+        nonlocal in_seqs, out_seqs, key_fn
+
+        in_seqs_rf, out_seqs_rf = reify((in_seqs, out_seqs), S)
+
+        if (
+            not any(isinstance(s, str) for s in in_seqs_rf)
+            and reduce(
+                lambda x, y: x == y and y, (length_hint(s, -1) for s in in_seqs_rf)
+            )
+            > 0
+        ):
+
+            in_seqs_ord = zip(*sorted(zip(*in_seqs_rf), key=partial(key_fn, S)))
+            S_new = unify(
+                list(out_seqs_rf),
+                [type(j)(i) for i, j in zip(in_seqs_ord, in_seqs_rf)],
+                S,
+            )
+
+            if S_new is not False:
+                yield S_new
+        else:
+
+            S_new = unify(out_seqs_rf, in_seqs_rf, S)
+
+            if S_new is not False:
+                yield S_new
+
+    return ground_order_seqs_goal
+
+
 def ifa(g1, g2):
     """Create a goal operator that returns the first stream unless it fails."""
 
@@ -204,22 +254,37 @@ def run(n, x, *goals, results_filter=None):
         return tuple(take(n, results))
 
 
-def dbgo(*args, msg=None):  # pragma: no cover
-    """Construct a goal that sets a debug trace and prints reified arguments."""
+def dbgo(*args, msg=None, pdb=False, print_asap=True, trace=True):  # pragma: no cover
+    """Construct a goal that prints reified arguments and, optionally, sets a debug trace."""  # noqa: E501
     from pprint import pprint
 
+    from unification import var
+
+    trace_var = var("__dbgo_trace")
+
     def dbgo_goal(S):
-        nonlocal args
-        args = reify(args, S)
+        nonlocal args, msg, pdb, print_asap, trace_var, trace
+
+        args_rf, trace_rf = reify((args, trace_var), S)
+
+        if trace:
+            S = S.copy()
+            if isvar(trace_rf):
+                S[trace_var] = [(msg, tuple(str(a) for a in args_rf))]
+            else:
+                trace_rf.append((msg, tuple(str(a) for a in args_rf)))
+                S[trace_var] = trace_rf
 
-        if msg is not None:
-            print(msg)
+        if print_asap:
+            if msg is not None:
+                print(msg)
+            pprint(args_rf)
 
-        pprint(args)
+        if pdb:
+            import pdb
 
-        import pdb
+            pdb.set_trace()
 
-        pdb.set_trace()
         yield S
 
     return dbgo_goal